The main parameters required to forecast lava flows are the eruption effusion rate, the lava viscosity, and the pre‐eruption topography. We focus on how the spatiotemporal resolution and vertical errors of topographic measurements affect lava flow forecasts. We develop a basic fluid mechanical flow model that, combined with theory, allows us to study the propagation of lava flows on simple noisy topography. We find that topographic noise acts to retard and widen the flow and show that relative noise greater than approximately 10% of the flow thickness significantly reduces the simulated advance rates and compromises the retrieval of the other eruption parameters. We also analyze how vertical topographic error, spatial sampling, and the time sampling frequency affect the effusion rate uncertainty. This work provides a basis for understanding how repeat topography data sampling and precision can affect forecasting lava flow spatiotemporal inundation and inform observation needs from future topography missions.

Improving forecasting of eruptive hazards is a top priority of the volcanological community and can be difficult to do in complex eruptions. From 2016 to 2022, Nevados de Chillán, Chile, underwent a complex eruption with multiple transitions between effusive and explosive activity, resulting in four domes and eight lava flows. We combine a decade of InSAR time series data with 4.5 years of data at five local GNSS stations to define three distinct periods of co-eruptive surface subsidence and three periods of co-eruptive uplift. We use Markov chain Monte Carlo methods to invert for the source depth and volume change necessary to cause each surface deformation period. We find evidence for the third uplift phase source to be slightly deeper (6.4 ± 0.4 km below ground level) compared to the first two periods of uplift (4.4 ± 0.2 km and 4.8 ± 0.1 km below ground level). We used topographic data from helicopter overflights and Pléiades and Maxar satellites to derive the total erupted volume ( 1.1 × 107 m3) between December 2017 and November 2022. We compare these data sets with optical imagery from Planet satellites, thermal time series from Terras ASTER instrument, and seismic data. Each effusive phase begins with larger effusion rates that taper off. The episodes of surface uplift coincide with increases in effusion rate and seismicity, indicating a new supply of magma. The combination of ground-based, airborne, and satellite-derived datasets provides dense spatial and temporal information on eruption evolution.

Ce chapitre décrit différentes techniques de mesure des déplacements de surface des volcans, essentiellement à l’aide de données radar, mais aussi à l’aide de données optiques à haute résolution. Il montre comment la télédétection a été utilisée pour développer des observations statistiques globales de l’activité volcanique, et comment les mesures de déplacement obtenues depuis l’espace peuvent être combinées avec d’autres observations de télédétection ou des instruments au sol. Le chapitre démontre la contribution des mesures de déplacement par satellite dans la gestion des crises volcaniques récentes. L’amélioration de la disponibilité des données présente un avantage pour la communauté scientifique et les observatoires volcanologiques pour gérer les situations de crise en permettant d’obtenir rapidement des mesures de déformations du sol. Toutefois, des progrès sont encore nécessaires pour la surveillance en temps réel des volcans.

Surface Topography and Vegetation (STV) is a NASA targeted observable for maturation into an observing system architecture. STV will acquire high-resolution, global height measurements, including bare surface land topography, ice topography, vegetation structure, and shallow water bathymetry. These measurements serve a broad range of science and applications objectives that span solid earth, cryosphere, biosphere and hydrosphere disciplines. A common set of measurements could meet many of the community needs. STV objectives would be best met by new observing strategies that employ flexible multi-source and sensor measurements from a variety of orbital and sub-orbital assets. Science and application objectives would be best met by new, 3-dimensional observations from lidar, radar, and stereoimaging. Simulations, experiments, data analysis and technology development in interferometric SAR, lidar and stereo photogrammetry approaches, platform options and system architectures will all mature STV toward an observing system.

Abstract Up‐to‐date topography data sets are essential for forecasting volcanic hazards and monitoring deformation. Digital elevation models are used to quantify eruption rates, used in flow modeling programs, and are necessary to accurately process interferometric synthetic aperture radar data for surface deformation. We can track topographic change at volcanoes through fieldwork, airborne instruments, and satellite data, with the last providing the greatest potential for global coverage. Despite this global coverage, we do not know the characteristics of topographic change at volcanoes over a given time interval. We define the specific acquisition needs for topography data using topographic change detected from recent eruptions. We review existing literature and compile a data set of eruptive products (121 lava flows, 99 domes and 163 pyroclastic density currents (PDCs)) from eruptions between 1980 and 2019. We find that different sensing capabilities are required for different use cases. A vertical accuracy of 1 m would detect 92% of all eruptive products including 100% of lava domes and lava flows, but only 78% of PDCs. A horizontal resolution of 13 × 13 m pixels is the minimum necessary to detect 90% of all eruptive products. Explosive eruptions (with PDC products) typically lasted less than 1 day and would need a temporal resolution of 1 day while a longer repeat interval is acceptable at effusive eruptions (lava domes and flows), which could last weeks to years. We find a lack of consistent data acquisition, with 45% of the 383 eruptive products reported not having published spatial dimensions.

Recent geodetic data has clearly imaged significant contraction of rift zones during effusive eruptions, which is attributed to deformation of active, elongated feeders, challenging the rigid conduit paradigm. In this work we develop a physical model to understand the impact of conduit deformation on the eruptive dynamics. Numerical calculations show that magma overpressure increases the width of the conduit, resulting in higher discharge rates than would be expected from the rigid case. At the same time, conduits with high aspect ratio, have larger compressibility and can store significant amount of magma, thereby acting as secondary reservoirs. The net result is that rift zones can maintain high fluxes over prolonged periods of time, leading to large volume eruptions and biasing magma compressibility estimates. We apply our findings to the 2018 Kīlauea eruption where episodic collapse of the summit led to pressure pulses that propagated down‐rift and that were recorded by both tiltmeters and peaks in the effusion rates. Inversion of the data indicates a conduit with a height of 700–800 m and a maximum opening of 4 m, located at a depth of 2.5 km in the Upper East Rift Zone, becoming shallower in the Puʻu ʻŌʻō region and propagating sub‐horizontally in the Middle and Lower East Rift Zone. Based on these properties we infer that up to 30% of the erupted volume can be attributed to magma stored in the rift zone. In agreement with recent studies, we find that magma over‐pressure was low at the end of the 2018 eruption.

Earth and Space Science Open Archive Presented WorkOpen AccessYou are viewing the latest version by default [v1]Initial Geophysical characterization of crustal deformation following the May 2021 Nyiragongo eruption and GPS network design for continued studyAuthorsDerrickMurekeziiDAndrewNewmanChristelleWauthierCynthiaEbingeriDJuditGonzalez SantanaPaulLundgrenSee all authors Derrick MurekeziiDCorresponding Author• Submitting AuthorGeorgia TechiDhttps://orcid.org/0000-0002-9690-5140view email addressThe email was not providedcopy email addressAndrew NewmanGeorgia Techview email addressThe email was not providedcopy email addressChristelle WauthierThe Pennsylvania State Universityview email addressThe email was not providedcopy email addressCynthia EbingeriDTulane University of LouisianaiDhttps://orcid.org/0000-0002-6211-3399view email addressThe email was not providedcopy email addressJudit Gonzalez SantanaThe Pennsylvania State Universityview email addressThe email was not providedcopy email addressPaul LundgrenJet Propulsion Laboratory, California Institute of Technologyview email addressThe email was not providedcopy email address

Understanding the processes that govern the inter-eruptive dynamics of volcanic calderas (e.g., Campi Flegrei, Yellowstone) is crucial to detect unrest and better forecast their activity. This is an important concern to monitoring agencies because calderas may represent major hazards to modern societies, both at local and global scale. One of the most intriguing caldera-related phenomena is the so-called breathing, i.e., continuous inflation-deflation cycles on the order of up to 10s of centimeters per year and with characteristic periodicities ranging from a few years to decades. In this study, we explore the breathing activity of Domuyo volcano (Argentina), a dacitic-rhyolitic caldera in the Southern Andes whose most recent eruption occurred >10,000 years ago (Lundgren et al., 2020); and the recent breathing phase leading to the moderate (volcano explosivity index 3) eruption in January 2020 at Taal volcano (Philippines). In particular, we integrate geodetic data (retrieved from the synthetic aperture radar -SAR- sensors onboard ALOS, ALOS-2, Radarsat-2, and Sentinel-1 satellites) with a recently discovered observable found to emerge on active volcanoes during unrest (Girona et al., 2021): low-temperature (~1 K over ambient temperature), large-scale (up to 10s of km2), long-term ( 6 months/1 year) thermal anomalies (retrieved from the moderate resolution imaging spectroradiometers -MODIS- onboard NASA’s Terra and Aqua satellites). Our analysis shows that geodetic and thermal unrest are significantly correlated, although the time series are phase shifted. To interpret these phase shifts and their implications, we develop a first-order, 1D numerical model based on mass, momentum, and energy conservation that couples the permeable flow of gases through the shallow crust, the viscoelastic deformation of the crust, the condensation of magmatic water vapor in the subsurface, and the diffusive transport of heat to the surface. Our preliminary results show that: (i) phase shifts between thermal and geodetic time series are controlled by detection limits, and by the coupling between magma reservoir processes and the transport of gas and heat through the crust; (ii) the pressure inside magma reservoirs can oscillate spontaneously during quiescent outgassing at the typical breathing timescales, thus suggesting that some geodetic and thermal unrest episodes are not necessarily associated to new magma inputs, but to the intrinsic dynamics of active magma reservoirs. This study has important implications for assessing volcanic hazards through improved eruption forecasting methods. Girona, T., Realmuto, V. & Lundgren, P. Large-scale thermal unrest of volcanoes for years prior to eruption. Nat. Geosci. 14, 238–241 (2021). https://doi.org/10.1038/s41561-021-00705-4. Lundgren, P., Girona, T., Bato, M.G. et al. The dynamics of large silicic systems from satellite remote sensing observations: the intriguing case of Domuyo volcano, Argentina. Sci Rep 10, 11642 (2020). https://doi.org/10.1038/s41598-020-67982-8.

First posted December 19, 2022 For additional information, contact: Director, Volcano Science CenterU.S. Geological Survey1300 SE Cardinal CourtVancouver, WA 38683 A significant number of the world's approximately 1,400 subaerial volcanoes with Holocene eruptions are unmonitored by ground-based sensors yet constitute a potential hazard to nearby residents and infrastructure, as well as air travel and global commerce. Data from an international constellation of more than 60 current satellite instruments provide a cost-effective means of tracking activity and potentially forecasting hazards at volcanoes around the world. These data span the electromagnetic spectrum: ultraviolet, optical, infrared, and microwave (synthetic aperture radar). They can measure volcanic thermal and gas emissions, ground displacement, and surface and topographic change, providing information that addresses one of the grand challenges in volcanology—to overcome our incomplete understanding of the relation between volcanic unrest and eruption, which is currently based on only a few well-studied volcanoes.Although the potential of volcano remote sensing has been recognized for decades, there are many hurdles to clear before remote sensing data can be used fully by all volcano observatories. These include: (1) the limited temporal and spatial coverage of active volcanoes by satellites and the delayed distribution of those data; (2) the lack of background data acquired at all volcanoes; and (3) limited access to, and utilization of, remote sensing data in some areas owing to a lack of expertise, licensing, user-friendly formats, data access portals, or computational infrastructure.While remote sensing data will never replace ground-based monitoring, a joint observation strategy provides a powerful means of assessing volcanic activity before, during, and after hazardous eruptions, especially given the unique spatial, temporal, and spectral perspective provided by remote measurements. A coordinated international remote sensing observation strategy for volcanoes—similar to one used by the cryosphere community—along with a volcano space task group to maximize the utility of satellite data for volcano monitoring would be highly beneficial. Such a vision could facilitate (1) global coordination of satellite observations (as done for polar regions) for background monitoring and eruption response, (2) open data that can be rapidly distributed during crises, (3) communication tools and forums for discussion of satellite data, (4) integrated ground and satellite databases of unrest, and (5) global capacity building.

Recent large basaltic eruptions began after only minor surface uplift and seismicity, and resulted in caldera subsidence. In contrast, some eruptions at Galápagos Island volcanoes are preceded by prolonged, large amplitude uplift and elevated seismicity. These systems also display long-term intra-caldera uplift, or resurgence. However, a scarcity of observations has obscured the mechanisms underpinning such behaviour. Here we combine a unique multiparametric dataset to show how the 2018 eruption of Sierra Negra contributed to caldera resurgence. Magma supply to a shallow reservoir drove 6.5 m of pre-eruptive uplift and seismicity over thirteen years, including an Mw5.4 earthquake that triggered the eruption. Although co-eruptive magma withdrawal resulted in 8.5 m of subsidence, net uplift of the inner-caldera on a trapdoor fault resulted in 1.5 m of permanent resurgence. These observations reveal the importance of intra-caldera faulting in affecting resurgence, and the mechanisms of eruption in the absence of well-developed rift systems.

Volcano monitoring and eruption response is centered on local volcano observatories who are informed through their local networks of in situ instruments, especially seismometer and Global Navigation Satellite System (GNSS) geodetic time series. Interferometric synthetic aperture radar (InSAR) has an increasing role in volcano monitoring. Typically, this occurs with InSAR providing context during episodes of unrest and eruption, usually with a request by the local observatory to relevant scientists. Here we provide some examples of recent InSAR contributions to volcano unrest and eruption, mostly from satellite InSAR, but also with an example from single pass airborne interferometry for topography change during the 2018 Kilauea eruption. We will conclude by pointing towards future directions applying large scale processing combined with dynamical volcano modeling to aid system forecasting.

The 2018 eruption on the lower East Rift Zone of Kīlauea Volcano produced one of the largest and most destructive lava flows in Hawai’i during the past 200 years. Over the course of more than 3 months, twenty-four fissures erupted, and the rate of lava effusion varied by two orders of magnitude, with significant implications for evolving flow behavior and hazards. Syn-eruptive data were collected to quantify these changes in lava effusion rate, including video of flow through channels and digital elevation models acquired using small unoccupied aircraft systems, airborne lidar, and airborne single-pass interferometric synthetic aperture radar. Topographic data through time allowed calculation of subaerial lava flow volume and time-averaged discharge rate over the course of the eruption, which we integrated with pre- and post-eruption bathymetric surveys. Repeat videos of the near-vent channel were analyzed with particle velocimetry to extract flow velocities, and these were combined with open channel flow theory to calculate a time series of instantaneous effusion rates. Results show a general increase in dense rock equivalent (DRE) effusion rate from ~7 to ~100 m 3 /s from early to late May for the whole flow field and ≥ 200 m 3 /s by mid-June after the eruption had focused at a primary vent. By the end of the eruption in August, 0.9–1.4 km 3 DRE of lava had erupted, with 0.4 km 3 deposited on land and at least 0.5 km 3 offshore. The trends in effusion rate through time reflect magmatic processes in the connected summit and rift zone system that controlled eruption rate, with resulting implications for lava flow dynamics and hazards.

Eruptions at shield volcanoes often occur from radially aligned linear fissures fed by blade‐like magma‐filled cracks (dykes). The fissures of the 2018 Sierra Negra eruption were scattered on the flank of the volcano. Space‐borne radar interferometric data (interferometric synthetic aperture radar) revealed that, unexpectedly, part of the eruption was fed by a 15 km long, tortuous and flat‐lying crack (sill). Here we develop a framework that captures the full three‐dimensional (3D) kinematics of non‐planar intrusions. This includes both an analytical and comprehensive numerical scheme. We constrain the models such that they match the observed ground deformation at Sierra Negra. We show that the peculiar sill trajectory is due to the competing stress gradient magnitudes being close to one another throughout its propagation. By accounting for the interaction of all these factors, these 3D models open the possibility to understand and simulate the geometry of magma transport at volcanic systems.

Volcano monitoring is centered around volcano observatories that rely on local networks of in situ instruments to monitor activity in near-real time. Primary observations include seismicity, surface deformation, and thermal and gas emissions. Satellite remote sensing observations of surface deformation (from interferometric synthetic aperture radar; InSAR) and spectroscopic data are showing increasing potential for volcano monitoring as their availability and quality improve. Here we present new insights we derive from the combination of InSAR and thermal time series on driving models for volcano processes, and their implications for volcano monitoring. We present analyses of three volcanoes: Domuyo (Argentina), Taal (Philippines), and Nevados de Chillán (Chile), whose geodetic time series show a deflation-inflation striking pattern. We discuss the implications of these observations for volcano dynamics at these diverse volcanic systems.

The largest effusive basaltic eruptions are associated with caldera collapse and are manifest through quasi-periodic ground displacements and moderate-size earthquakes 1 – 3 , but the mechanism that governs their dynamics remains unclear. Here we provide a physical model that explains these processes, which accounts for both the quasi-periodic stick–slip collapse of the caldera roof and the long-term eruptive behaviour of the volcano. We show that it is the caldera collapse itself that sustains large effusive eruptions, and that triggering caldera collapse requires topography-generated pressures. The model is consistent with data from the 2018 Kīlauea eruption and allows us to estimate the properties of the plumbing system of the volcano. The results reveal that two reservoirs were active during the eruption, and place constraints on their connectivity. According to the model, the Kīlauea eruption stopped after slightly more than 60 per cent of its potential caldera collapse events, possibly owing to the presence of the second reservoir. Finally, we show that this physical framework is generally applicable to the largest instrumented caldera collapse eruptions of the past fifty years.

Identifying the observables that warn of volcanic eruptions is a major challenge in natural hazard management. A potentially important observable is the release of heat through volcano surfaces, which represents a major energy source at quiescent volcanoes. However, it remains unclear whether surface heat emissions respond to pre-eruptive processes and vary before eruption. Here we show through a statistical analysis of satellite-based long-wavelength (10.780–11.280 μm) infrared data that the last magmatic and phreatic eruptions of five different volcanoes were preceded by subtle but significant long-term (years), large-scale (tens of square kilometres) increases in their radiant heat flux (up to ~1 °C in median radiant temperature). Large-scale thermal unrest is detected even before eruptions that were not anticipated from other volcano monitoring methods, such as the 2014 phreatic eruption of Ontake (Japan) and the 2015 magmatic eruption of Calbuco (Chile). We attribute large-scale thermal unrest to the enhancement of underground hydrothermal activity, and suggest that such analysis of satellite-based infrared observations can improve constraints on the thermal budget of volcanoes, early detection of pre-eruptive conditions and assessments of volcanic alert levels.

In this work, we investigate the April 4, 2010, M w 7.2 El Mayor Cucapah (EMC) earthquake. Existing studies modeled the EMC area as an elastic half‐space in a homogeneous or vertically layered structure, which, along with differences in data and inversion methodologies, led to considerable variability in the resultant fault slip models. To investigate the EMC earthquake more realistically, we first examine how published coseismic fault slip models have approached the problem and what are their findings, then we select the optimal geometry and slip of one most recent and comprehensive coseismic fault slip model, obtained through analytical inversions, and adapt them in a three‐dimensional finite element numerical environment where we assess the effects of topography and material heterogeneities. Numerically optimized slip models are obtained via joint inversion of GPS, interferometric synthetic aperture radar, and subpixel offset data sets. We find the effect of topography to be negligible while the inclusion of material heterogeneities enhances the slip at depth, as might be expected where the medium has higher rigidity, and better fits the displacements at both near and far field, especially around the Salton Sea area. The match with geodetic data is significantly improved when the fault slip is increased at the fault planes close to the epicenter and deeper at the southernmost plane, with respect to the slip of the chosen analytical model. Our findings suggest that this earthquake was associated with a higher and more spatially concentrated slip than previously thought implying a greater stress drop at depth.

Changes in groundwater storage in California's Central Valley (CV) are considered partly responsible for vertical uplift surrounding the southern CV and for stress changes on nearby faults. Questions remain regarding the distribution of stress on the central San Andreas fault (CSAF) from recent and historical drawdown of the CV aquifer over the past 150 years (1860–2010). We combine groundwater storage change estimates for the 2006–2010 drought with a three‐dimensional finite element model to estimate Coulomb failure stress change (ΔCFS) on the CSAF. We combine a simple parameterization of historical hydraulic head change for 1860–1960 with a CV hydrological model (1961–2003) to estimate visco‐elastic effects on ΔCFS total and 2010 rate. We find that ΔCFS on the CSAF correlates positively with shallow seismicity and low frequency earthquakes for both short‐term and long term stressing. Unloading uplift rates surrounding the southern CV only partially account for the observed vertical GPS rates.

On January 12, 2020, Taal volcano, Philippines, erupted after 43 years of repose, affecting more than 500,000 people. Using interferometric synthetic aperture radar (InSAR) data, we present the pre‐ to post‐eruption analyses of the deformation of Taal. We find that: (1) prior to eruption, the volcano experienced long‐term deflation followed by short‐term inflation, reflecting the depressurization‐pressurization of its ∼5 km depth magma reservoir; (2) during the eruption, the magma reservoir lost a volume of 0.531 ± 0.004 km 3 while a 0.643 ± 0.001 km 3 lateral dike was emplaced; and (3) post‐eruption analyses reveal that the magma reservoir started recovery approximately 3 weeks after the main eruptive phase. We propose a conceptual analysis explaining the eruption and address why, despite the large volume of magma emplaced, the dike remained at depth. We also report the unique and significant contribution of InSAR data during the peak of the crisis.